Fixed dependency of publish-internal task
The Ceylon ant tasks library is no longer copied to the Ceylon repository but can be found in the distribution lib folder instead
The compiler jar now gets generated directly in the final build/repo/... folder instead of first to build/lib and then copying it
Removed unused tasks for creating the docs for the language module
The launcher `run()` method now returns the exit code of the code that was executed. While `main()` will now use `System.exit(run())`.
Temporary HACK to make multiple executions in the same JVM possible (WARNING: leaks a LOT of memory!)